Greater than 20% of individuals with cerebral malaria (CM) suffer from persistent neurological and cognitive deficits long after successful anti-parasitic treatment. These deficits encompass a wide range of neuro-cognitive dysfunction. We have demonstrated in a murine model that CM results in a vasculopathy with increased levels of endothelin- 1 (ET-1), leading to a reduction of cerebral blood flow and a decrease in NAA/Cr ratio in the brains of mice on MRS [2]. Our preliminary data also demonstrate that just as with human disease, mice sustain cognitive dysfunction [42], which persists even after successful eradication of the parasite, as evidenced by significantly impaired performance in object recognition and spatial memory tests. Furthermore, CM mice had significant motor coordination deficits on the balance beam even after successful antiparasitic treatment. These cognitive and motor impairments were still evident on retesting 40 days after resolution of malarial infection. However, they were not accompanied by any significant degree of vascular damage, inflammation or astrogliosis. The lack of obvious pathology after parasitic cure suggests that these long-term neuro- cognitive deficits are the result of potentially reversible biochemical and physiological changes in brains of CM mice subsequent to the decreased blood flow and ischemia during the acute infection. We demonstrated that tau, a protein involved in neurofibrillary tangle formation in Alzheimer's disease, is aberrantly phosphorylated in cortical neurons of infected mice during CM. We believe that the aberrant tau phosphorylation is the end product of an altered signaling in the neurons of infected mice mediated by ET-1. We have found a down-regulation of the PI3K/Akt insulin signaling/ survival pathway in the brains of mice with CM. As a result of decreased Akt activation, the normal inhibition of GSK3 by Akt does not occur and tau becomes aberrantly phosphorylated. In addition, Akt is no longer able to facilitate the translocation of glucose transporters to the cell membranes and the cells are not able to uptake glucose. We propose that as a result of a reduction in cerebral blood flow, there is ischemia and neuronal damage associated with abnormalities in the insulin signaling/ survival pathway. This mechanism likely underlies the cognitive function impairment observed in CM and may yield therapeutic targets for adjunctive therapy in the management of CM.

Public Health Relevance

Malaria is an important cause of morbidity and mortality especially in sub-Saharan Africa where children bear the greatest burden. Cerebral malaria is a form of severe malaria caused mainly by Plasmodium falciparum in humans. This form of malaria is often associated with neurological sequelae including seizures, memory impairment and behavior disturbances. In the mouse model of cerebral malaria, mice are infected with the ANKA strain of Plasmodium berghei and compared to a non cerebral malaria model- mice infected with the NK65 strain of P. berghei. These mice have cognitive dysfunction and other neurological abnormalities not seen with the non cerebral malaria mice. We also have evidence of a reduction in cerebral blood flow in this model. Dysregulation of tau protein which is important in the dementia of Alzheimer's disease and abnormalities in the regulation of Akt- one of the signaling pathways that is important in cell survival and glucose regulation- are also present in the mouse model of malaria. Thus, vascular compromise and alterations in Akt and tau may be important in the pathogenesis of malaria and may provide rational targets of drug therapy to ameliorate the consequences of this infection.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
1R01NS069577-01A1
Application #
8110384
Study Section
Pathogenic Eukaryotes Study Section (PTHE)
Program Officer
Wong, May
Project Start
2011-04-15
Project End
2016-02-29
Budget Start
2011-04-15
Budget End
2012-02-29
Support Year
1
Fiscal Year
2011
Total Cost
$365,967
Indirect Cost
Name
Albert Einstein College of Medicine
Department
Pathology
Type
Schools of Medicine
DUNS #
110521739
City
Bronx
State
NY
Country
United States
Zip Code
10461
D'Orléans-Juste, Pedro; Akide Ndunge, Oscar B; Desbiens, Louisane et al. (2018) Endothelins in inflammatory neurological diseases. Pharmacol Ther :
Freeman, Brandi D; Martins, Yuri C; Akide-Ndunge, Oscar B et al. (2016) Endothelin-1 Mediates Brain Microvascular Dysfunction Leading to Long-Term Cognitive Impairment in a Model of Experimental Cerebral Malaria. PLoS Pathog 12:e1005477
Pekson, Ryan; Poltoratsky, Vladimir; Gorasiya, Samir et al. (2016) N,N-Dimethylacetamide Significantly Attenuates LPS- and TNF?-Induced Proinflammatory Responses Via Inhibition of the Nuclear Factor Kappa B Pathway. Mol Med 22:747-758
Martins, Yuri C; Freeman, Brandi D; Akide Ndunge, Oscar B et al. (2016) Endothelin-1 Treatment Induces an Experimental Cerebral Malaria-Like Syndrome in C57BL/6 Mice Infected with Plasmodium berghei NK65. Am J Pathol 186:2957-2969
Vyas, Vibhuti; Ashby Jr, Charles R; Olgun, Nicole S et al. (2015) Inhibition of sphingosine kinase prevents lipopolysaccharide-induced preterm birth and suppresses proinflammatory responses in a murine model. Am J Pathol 185:862-9
Olgun, Nicole S; Hanna, Nazeeh; Reznik, Sandra E (2015) BQ-123 prevents LPS-induced preterm birth in mice via the induction of uterine and placental IL-10. Toxicol Appl Pharmacol 282:275-84
Munnangi, S; Gross, S J; Madankumar, R et al. (2014) Pregnancy associated plasma protein-A2: a novel biomarker for Down syndrome. Placenta 35:900-6
Freeman, Brandi D; Machado, Fabiana S; Tanowitz, Herbert B et al. (2014) Endothelin-1 and its role in the pathogenesis of infectious diseases. Life Sci 118:110-9
Nagajyothi, Fnu; Kuliawat, Regina; Kusminski, Christine M et al. (2013) Alterations in glucose homeostasis in a murine model of Chagas disease. Am J Pathol 182:886-94
Sundaram, Sruthi; Ashby Jr, Charles R; Pekson, Ryan et al. (2013) N,N-dimethylacetamide regulates the proinflammatory response associated with endotoxin and prevents preterm birth. Am J Pathol 183:422-30

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